To the Editor. —In their article, "Retinal Light Exposure From Operation Microscopes" (Archives97:2363-2367, 1979), Calkins and Hochheimer present an excellent analysis of the potential problems resulting from retinal irradiance from operating microscopes. The authors suggest that there may be a correlation between retinal light exposure and the incidence of postsurgical cystoid maculopathy and that this possibility warrants further investigation. Unpublished data from a preliminary study of this possibility are available. At the Washington University (St Louis) Department of Ophthalmology, we studied 28 eyes from 26 patients undergoing routine surgery for senile cataracts. Subjects were matched for age, sex, race, and systemic and ocular disease. Eyes with significant macular disease evident preoperatively were eliminated, as were those with intraocular complications. Thirteen of the eyes underwent lens extraction under standard conditions using an operating microscope (Weck) and overhead lighting. The experimental group of 15 eyes had a specially designed opaque contact